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Wear rings for downhole pumpRelated Patent Categories: Pumps, Expansible Chamber Type, Fluid Serially Moved To Opposite Side Of Pumping MemberWear rings for downhole pump description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20050265875, Wear rings for downhole pump. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] This application claims the benefit of U.S. patent application, Ser. No. 60/574,143, filed May 25, 2004. FIELD OF THE INVENTION [0002] The present invention relates to subsurface or downhole pumps such as are used to pump oil and other fluids in bases for oil wells. BACKGROUND OF THE INVENTION [0003] When an oil well is first drilled and completed, the fluids (such as crude oil) may be under natural pressure that is sufficient to produce on its own. In other words, the oil rises to the surface without any assistance. [0004] In many oil wells, and particularly those in fields that are established and aging, natural pressure has declined to the point where the oil must be artificially lifted to the surface. Subsurface, or downhole, pumps are located down in the well below the level of the oil. A string of sucker rods extends from the pump up to the surface to a pump jack device, or beam pump unit. A prime mover, such as a gasoline or diesel engine, or an electric motor, or a gas engine on the surface causes the pump jack to rock back and forth, thereby moving the string of sucker rods up and down inside of the well tubing. [0005] The string of sucker rods operates the subsurface pump. A typical pump has a plunger that is reciprocated inside of a barrel by the sucker rods. The barrel has a standing one-way valve, while the plunger has a traveling one-way valve, or in some pumps the plunger has a standing one-way valve, while the barrel has a traveling one-way valve. Reciprocation charges a chamber between the valves with fluid and then lifts the fluid up the tubing toward the surface. [0006] The clearance between the plunger and barrel allows one to reciprocate easily and smoothly with respect to the other. This clearance is large enough to be lubricated by the downhole fluids and small enough to prevent leakage of fluid around the pump valves. [0007] In normal use, the pump barrel and plunger experience wear. The wear leads to loss of performance of the lifting ability of the pump. Well fluid leaks around the traveling valve and the plunger; consequently the differential pressures across the valve that are necessary for its operation are unable to develop. [0008] To repair the pump, the pump must be pulled from the well. The components are inspected and any worn components are replaced. Pulling the pump and replacing components results in downtime for the well and expense in the operation of the well. In normal use, a pump may last between three months to a year before it is pulled for repair. [0009] In wells that produce sand, a pump may last only a few weeks. The sand abrades the ends of the reciprocating component and eventually enters the clearance between the plunger and the barrel, causing wear. Consequently, the pump components must be replaced more often. [0010] Barrels and plungers are typically made of relatively soft material, having Rockwell hardness of C20. The barrels and plungers could be made of a harder material but they would be brittle and not as durable in the well. Instead, the barrels and plungers are treated on their wear surfaces so as to harden the wear surfaces. Such surface treatments include carbonizing, chroming and spray metal. Yet these treated surfaces quickly degrade in wells that produce sand. SUMMARY OF THE INVENTION [0011] It is an object of the present invention to provide an increase in the durability of pump components such as plungers and barrels. [0012] A plunger is provided for use in a downhole pump. The plunger has an elongated body. At least portions of the body have an outside diameter that is structured and arranged to reciprocate relative to a barrel. The outside diameter has first and second ends. The outside diameter has a surface that has a first hardness. An inner passage runs through the body along the length thereof. Rings are located at the first and second ends, the rings made of a second material having a second hardness. The second hardness is greater than the first hardness. [0013] In accordance with one aspect of the present invention, the rings have a hardness that exceeds Rockwell C70. [0014] In accordance with another aspect of the present invention, the first and second ends each have a groove for receiving one of the rings. [0015] In accordance with another aspect of the present invention, the rings have a first outside diameter and the plunger has a second outside diameter which is larger than the first outside diameter, the plunger second outside diameter structured and arranged to wear down to the first outside diameter. [0016] The present invention also provides a barrel for use in a downhole pump. The barrel comprises an elongated body. A passage extends along the length of the barrel. At least portions of the body have an inside diameter around the passage, which passage is structured and arranged to receive a plunger. The inside diameter having first and second ends. The inside diameter has a surface that has a first hardness. Rings are located at the first and second ends. The rings are made of a second material having a second hardness. The second hardness is greater than the first hardness. [0017] In accordance with one aspect of the present invention, the rings have a hardness that exceed Rockwell C70. [0018] In accordance with another aspect of the present invention, the first and second ends each have a groove for receiving one of the rings. [0019] In accordance with another aspect of the present invention, the rings have a first inside diameter and the barrel has a second inside diameter which is smaller than the first inside diameter, the barrel second inside diameter being structured and arranged to wear to the first inside diameter. [0020] The present invention also provides a downhole pump having a barrel and a plunger. The barrel has a passage extending along the length of the barrel, with the passage having an inside diameter. The plunger has a plunger passage extending along the length of the plunger, with the plunger having an outside diameter. The plunger is received by the barrel passage for relative reciprocal movement. One of the barrel or the plunger has the respective diameter having a surface with a first hardness and having two ends. The ends have rings. The rings are made of a second material having a second hardness. The second hardness is greater than the first hardness. [0021] In accordance with another aspect of the present invention, the one of the barrel or plunger is the shorter of the barrel or plunger. Continue reading about Wear rings for downhole pump... 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